1. Field of the Invention
The present invention relates to sheet feeding devices, and more particularly to a device for feeding recordable papers to an image forming apparatus.
2. Description of the Related Art
Generally, an image forming apparatus has a structure such that in a case of printing, a recordable paper is automatically fed thereto so that the printing is continuously performed and in a case of scanning, a document to be scanned is manually fed through a separate path different from that of feeding the recordable paper so that the scanning is performed.
An exemplary earlier image forming apparatus has a port for feeding the recordable paper formed on a side of a body of the apparatus, in which a main frame is mounted. A knock-up plate, on which the recordable papers are stacked, is mounted and supported by a knock-up spring on the main frame. A pick-up roller is disposed on an upper surface of an end portion of the knock-up plate to move the recordable paper toward a feed roller. On the other hand, a port for feeding a document to be scanned is formed below the main frame so that the document is fed.
A plurality of idle rollers are mounted on a rotating shaft having a pick-up roller mounted thereon to guide the recordable paper. A pick-up cam is disposed at an end of the rotating shaft to shift the knock-up plate as the pick-up roller is rotated.
An end of the pick-up cam functions as a pressure bar contacting with the projection formed at a side of the knock-up plate and the other end of the pick-up cam functions as a support contacting with the pressure lever of the finger lever. The finger lever is positioned at a side of the main frame to feed the recordable paper. The finger lever includes an arm which extends horizontally from the hinge axis and has a finger at an end thereof, and a pressure lever which extends vertically from the hinge axis and is in contact with the support of the pick-up cam at an end thereof.
A finger spring is disposed between the main frame and the arm. The arm is supported by the finger spring on the main frame.
An operation of the device for feeding the recordable paper to the image forming apparatus according to the conventional art will be described. In the standby state, the knock-up plate is positioned by the pick-up cam at a bottom of the main frame. In the state, a knock-up spring is compressed.
As the pick-up roller rotates clockwise, the pick-up cam rotates together with the pick-up roller. Thus, the projection of the knock-up plate, which is restrained by the pressure bar, is released from the restrained state. The knock-up plate is shifted upward by means of a resilient force of the knock-up spring in the main frame.
At the same time, the pressure lever of the finger lever, which is restrained by the support of the pick-up cam, is also released from the restrained state so that the finger lever is counterclockwise rotated by means of the resilient force of the finger spring. Therefore, the recordable paper is in close contact with the pick-up roller by means of the knock-up plate shifted upward while being fed by means of the finger one by one as the finger lever rotates counterclockwise.
In this earlier device for feeding the recordable paper to the image forming apparatus, however, since the port for feeding a document to be scanned is separated from the port for feeding the recordable paper, there is a disadvantage in that the body must be moved in a direction for performing a feed of the document to be scanned every when scanning. Furthermore, as the path for feeding the recordable paper is different from the path for feeding the document, there is another disadvantage in that since an AC adapter is required for feeding the document, a structure of the image forming apparatus is complex. When the mode is converted from a recordable paper feeding mode to a document feeding mode or from the document feeding mode to the recordable paper feeding mode, the recordable paper stacked on the knock-up plate is substituted for the document to be scanned, or the document is substituted for the recordable paper.
Another example of a sheet feeder of the contemporary art is seen in U.S. Pat. No. 4,896,871, to Idenawa, entitled Sheet Feeder For An Image Recording Apparatus. This patent describes a sheet feeder for a laser printer which can be operated in manual or automatic sheet feeding mode, and which does not require a release lever for manual feeding.
Based on my observation of the art, then, I have found that what is needed is an apparatus min which the document to be scanned can be fed along the same path as the recordable paper.